Low formaldehyde release reactant

ABSTRACT

Textile treating agent for imparting crease resistance is made by mixing 1 mol glyoxal, 2 mols formaldehyde, 1 mol urea and 1.5 mol ethylene glycol and reacting the mixture first at pH 6 to 7 at 60 DEG C. and then at pH 3 at 60 DEG . The product is found to have more stable formaldehyde release properties in textile treating baths as pH of the bath is varied in the range from about 3.0 to about 4.5.

The invention relates to improvements in certain textile finishingagents and in making such agents and in their use. More particularly theinvention provides an improved method of making textile finishing agentsfor imparting crease resistance to cotton and cotton-polyester blendfabrics and the like.

The finishing agents of the invention would seem to resemble thosedescribed in U.S. Pat. No. 4,396,391 which were prepared by reactingdimethyloldihydroxyethylene urea (DMDHEU) with a polyol. In that patent,DMDHEU was reacted with a polyol such as ethylene glycol at pH 3.0 andfabrics treated with the product were shown to be comparable in wrinkleresistance to those treated with DMDHEU alone or those treated with anunreacted mixture of DMDHEU and the polyol. The reaction of this productin the fabric treatment process was shown to cause lower freeformaldehyde release than when the DMDHEU glycol mixture was used forthe fabric treatment. The pH of treating solutions that were used forthe fabric treatment was not described in the patent.

We found that the textile finishing agents made by reacting DMDHEU withethylene glycol as described in that patent would release lessformaldehyde in the fabric treating process, as the patent hadpredicted, in treating baths having pH about 3.0 to 3.5, but when the pHof the baths was increased to values above that range the formaldehyderelease rate was found to increase rapidly. It was therefore necessaryto carefully maintain the treating baths in a very close pH range tomaintain the advantage of low formaldehyde release.

A prior art method for making DMDHEU involved the reaction of one moleof urea, one mole of glyoxal and two moles of formaldehyde. Thoseingredients were mixed together and reacted at pH about 6.0 and 7.0 fortime long enough to complete the reaction, preferably about 3 hours attemperature about 60° C. The reaction product, DMDHEU, could then bereacted with one mole of ethylene glycol at about pH 3 and at reactiontemperature, e.g. 60° C., to make the reacton product described in U.S.Pat. No. 4,396,391.

It is an object of the invention to improve the formaldehyde releaseproperties of DMDHEU-glycol reaction products of the kind described, bymaking those reaction products in a different way.

In a preferred embodiment of the invention, a reaction mixturecomprising an aqueous solution of urea, glyoxal, formaldehyde andethylene glycol is made and the pH is adjusted to about pH 6 to 7 andthe mixture is reacted at reaction temperature about 60° C. for aboutthree hours. Then the pH of the mixture is adjusted to about pH 3 andthe reaction is continued for about one hour. This second reaction maybe carried out at other pH in the range from about 3.5 to 1.0 and forlonger reaction times. The reaction temperature may also be varied fromabout 40° C. to about 80° C. The product mixture is cooled and its pH isadjusted to about 4.5 to 5.5. The product mixture is then ready for useas a textile finishing agent and the product can be diluted with waterto the concentration wanted.

The difference between the method of the invention and the prior artmethod is the addition of glycol before the first reaction is carriedout at pH 6 to 7 rather than addition of the glycol after that firstreaction has been completed. One might expect to obtain the samereaction product by either method. The products do have the sameappearance and both impart about the same crease resistant properties tofabrics. It is found, however, that the products of the invention havesignificantly different formaldehyde release properties when usedinstead of the prior art products for textile finishing. In particular,the new products have more stable formaldehyde release properties as pHof the textile treating bath is varied through the range about pH 3 toabout pH 4.5. This and other advantages of the invention are illustratedby reference to the following specific examples which include detaileddescription of the best mode now contemplated for carrying out theinvention.

EXAMPLE 1

In a reaction vessel, one mole of glyoxal (40.3% glyoxal, 4.7%formaldehyde aqueous solution) is mixed with two moles of formaldehyde(50% formalin aqueous solution), one mole of urea and 1.5 moles ofethylene glycol. The pH of the mixture is adjusted by addition of NaOHto a value in the range from pH 6 to 7 and is maintained in that rangewhile the mixture is reacted at 60° C. for three hours. Then about 0.5%by weight of citric acid, based on weight of the finished product, isadded to the mixture and the pH is adjusted to pH 3.0 by addition of H₂SO₄. The temperature of the mixture is maintained at 60° C. for onehour, then cooled to about 25° C. and the pH is finally adjusted toabout pH 4.5 to 5.5 by addition of NaOH to make the finished productsolution.

EXAMPLE 2

For use as a control, another product is prepared by essentially thesame procedure described in Example 1 except the ethylene glycol isomitted from the original mixture but is added at the end of the threehour reaction period, just before the pH is adjusted to pH 3 and thereaction is carried out as before. The product is finished as in Example1.

EXAMPLE 3

A treating bath is preapred by mixing 10 parts by weight of the finishedproduct solution of Example 1 and one part by weight of a non-ionicsurfactant (Deceresol NI conc.) and 2.5 parts by weight of a selectedaccellerator catalyst solution with water to make 100 parts by weight ofthe bath solution. Separate bath solutions are made as described, eachwith one of the following accellerator catalyst solutions having thecomposition shown:

Catalyst No. 1. 30% MgCl, aqueous solution.

Catalyst No. 2. 15% MgCl+citric acid, aqueous solution.

The pH of the bath solutions before adjustment were in most cases aboutpH 3.0±0.2. Aliquots from each bath solution were adjusted to pH valuesfrom 3.0 to 4.5 at increments of 0.5. Similarly, bath solutions wereprepared by the same procedure but using the finished product solutionof Example 2. A preferred method for mixing the treating bath solutionsis to dilute each ingredient with water before addition.

EXAMPLE 4

Each bath solution described in Example 3 was used to impregnate asample of 100% cotton broadcloth shirting fabric and another sample ofD-C shirting fabric (65-35 cotton-polyester). Each fabric sample wasimpregnated by immersion using one dip and one nip, with padder pressureof one ton. The dry and cure was carried out by one pass through an ovenfor 48 seconds at 375° F.

EXAMPLE 5

Each 100% cotton fabric sample, treated as described in Example 4, wastested for wrinkle recovery using the Monsanto wrinkle recovery test.The test results are reported in Table I as the sum of the anglesmeasured in degrees in both the warp and fill directions (W+F).

                  TABLE I                                                         ______________________________________                                        Wrinkle Recovery (W + F)                                                      Agent Catalyst   pH 3.0  pH 3.5  pH 4.0                                                                              pH 4.5                                 ______________________________________                                        Ex. 1 No. 1      234     235     227   235                                    Ex. 2 No. 1      233     239     230   231                                    Ex. 1 No. 2      212     211     203   203                                    Ex. 2 No. 2      220     209     191   197                                    ______________________________________                                    

The formaldehyde release was measured by the AATCC Test Method No. 112for each sample of the D.C. shirting fabric treated as described inExample 4. Results are reported in ppm in Table II.

                  TABLE II                                                        ______________________________________                                        Formaldehyde Release (ppm)                                                    Agent Catalyst   pH 3.0  pH 3.5  pH 4.0                                                                              pH 4.5                                 ______________________________________                                        Ex. 1 No. 1      56      56      75     75                                    Ex. 2 No. 1      31      56      125   150                                    Ex. 1 No. 2      62      69      75     75                                    Ex. 2 No. 2      31      37      31    112                                    ______________________________________                                    

The results in Table I above show that the textile finishing compositionof the invention was practically equivalent to the prior art materialsin imparting wrinkle recovery to the treated textiles.

The comparison of formaldehyde release properties as shown in Table IIdemonstrates the advantage of far less variation in the amounts offormaldehyde released as pH of the treating baths is changed, when usingthe DMDHEU glycol reaction product of the invention (Example 1) insteadof the prior art textile treating agent (Example 2). The results willvary somewhat depending on the selected catalysts, but with all of thecatalysts that have been used with the new DMDHEU-glycol reactionproducts prepared as described in Example 1, the formaldehyde releaseproperty has been far more stable to variations in the pH of thetreating bath, than when other closely related DMDHEU-glycol productswere used.

In treatments of textiles using the finishing compositions of theinvention the formaldehyde release rates for all of the textile treatingbaths at all of the pH values tested, and with all of the catalyststested, were within a relatively narrow range. Over the same pH range,the prior art agent caused several fold increase in formaldehyde releaseas pH was increased. This demonstrates the excellent formaldehyderelease properties of the textile finishing agent of the invention. Thisagent will require less stringent pH control to maintain stableformaldehyde release in the textile treating operations.

We claim:
 1. An improved method for making textile finishing agentcomprising the steps ofmixing glyoxal, formaldehyde, urea and a glycoland reacting the mixture at temperature in the range from about 40° C.to about 80° C. and at pH in the range from 6 to 7 for time sufficientto complete the reaction and then changing the pH of the product mixtureand further reacting at temperature in the range from about 40° C. toabout 80° C. and at pH in the range from 3.5 to about 1.0 for timesufficient to complete the reaction and then adjusting the pH of theproduct mixture to pH in the range from pH 4.5 to 5.5.
 2. A textilefinishing agent comprising a product made by the process described inclaim
 1. 3. An aqueous solution of a textile finishing agent defined byclaim 2 further comprising a catalyst in said solution for thecross-linking reaction of the product with textile fabric.